Render vs Viewport render discrepancy
In your render the hair particles are not subdivided enough, check if these 2 settings match - first is for render, 2nd is for viewport:



Also in your render it seems there are more hairs rendered, that may be due to children particles and that only a percentage of them is displayed in viewport:



Lastly if you set the same amount of samples for viewport and render, you should get the same outcome: